class Solution {
public:
    int removeDuplicates(vector<int>& nums) 
    {
        int n = nums.size();
        if(n == 0) return 0;
        int fast = 1 , slow = 1;
        while(fast < n)
        {
            if(nums[fast] != nums[fast - 1])
            {
                nums[slow] = nums[fast];
                slow++;
            }
            fast++;
        }
        return slow;
    }
};//